16
\$\begingroup\$

I found a component attached to a PCB inside one of my old $5 devices. There are pink, rubbery things attached to either side of the LCD that can bend and were firmly attached (glued?), and there are a lot of exposed conductive traces where the pink things were attached on the PCB.

I would like to know what these pink things are. Pictures are shown below.

LCD

The front side of the LCD ^

LCD

The back side of the LCD ^

PCB

The front side of the PCB. This is where the LCD is connected to. ^

PCB

The back side of the PCB ^

Again, I would like to know what the pink things are.

\$\endgroup\$
24
\$\begingroup\$

Often called Zebra strips (or Elastomeric connectors). They have very thin vertical conductors that connect between flat PCB pads and things like LCD pads on glass.

Here is a link with a similar pink component.

http://en.wikipedia.org/wiki/Elastomeric_connector

\$\endgroup\$
  • \$\begingroup\$ The picture is exactly the same as what I have! \$\endgroup\$ – nimsson Mar 1 '15 at 18:35
  • \$\begingroup\$ One a typical hobbyist would use! According to the Ahmed clock hoaxer! \$\endgroup\$ – Bradman175 Nov 17 '16 at 8:24
9
\$\begingroup\$

As others note it's a "zebra connector" which conducts through the plane of the rubber but not across it (ie in the directions you'd expect for it to work).

The 'pitch' of the band s of conduction/non conduction are finer than the pitch of the contacts concerned so that short circuits are not formed between the contacts when the strip is moved "sideways".

Use an Ohm meter to measure resistance through the rubber between directly opposite points and then between points which are offset.
You will find that

  • When the probes are opposite each other there will be a low resistance path between them.

  • When the probes are offset by more than the thickness of the conductive bands that the resistance will be very high (or more :-) ).

This method allows ease of assembly, self alignment of the "connecter" - as long as the LCD contacts and PCB contacts are aligned the rubber strip alignment is non-crucial.

Zebra strip inter-stripe pitch too large - shorting can occur

█ = contact
▓ = zebra strip conductor
░ = zebra strip insulator

Alignment OK:

████  ████  ████  ████     
▓▓▓▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓▓░  
████  ████  ████  ████    

misaligned - shorts occur

████  ████  ████  ████      
▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓  
████  ████  ████  ████    

Zebra strip inter-stripe pitch small wrt conductor pitch - shorting can not occur

Alignment OK:

████  ████  ████  ████  
▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓    
████  ████  ████  ████    

misaligned - shorting still cannot occur

████  ████  ████  ████
░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓    
████  ████  ████  ████

See also this answer

\$\endgroup\$
  • 2
    \$\begingroup\$ Might benefit from a picture rather than ascii art :) \$\endgroup\$ – Wossname Nov 17 '16 at 9:30
  • \$\begingroup\$ @Wossname Och aye! Freel free :-). Maybe sometime but so far I am several thousand photos behind. \$\endgroup\$ – Russell McMahon Nov 17 '16 at 10:48
  • 2
    \$\begingroup\$ I tried replacing ASCII-art with UTF8-art, slight improvement? \$\endgroup\$ – RedGrittyBrick Nov 17 '16 at 16:50
  • \$\begingroup\$ @RedGrittyBrick, nice work. It's like going back to 1981 and squinting at a monochrome TV from 6 inches away. Love it. \$\endgroup\$ – Wossname Nov 17 '16 at 22:27
  • \$\begingroup\$ :-) ................................. \$\endgroup\$ – Russell McMahon Nov 18 '16 at 11:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.